With the ever increasing number of published manuscripts reporting peptide characterisation by reversed-phase chromatography coupled with mass spectrometric analysis, there is a pressing need to precisely define the instrument conditions used for these analyses. At present, instrument calibration and optimisation is performed on a laboratory-by laboratory basis, with no two facilities using the same criteria for instrument set-up. Many laboratories using multiple mass spectrometers for analysis of the same sample also use different standards for calibration and optimisation of the different instruments. In addition, the chromatographic conditions like solvents, solid-phase and elution gradient used for separation of peptides by reverse-phase are seldom the same. This makes both intra- and inter-laboratory comparisons of proteomics data almost impossible to perform with any degree of consistency.
EP 1 736 480 A1, Beynon et al., 2005 and Pratt et al., 2006 describe a Qcon-CAT methodology for the construction of tryptic peptide sequences but do not disclose a single polypeptide standard for optimising separation of peptides by reversed-phase chromatography and their detection and fragmentation by mass spectrometry, in addition to maintaining reproducibility in proteomics experiments, which requires that instrument parameters be optimised and standardised according to defined criteria. No single standard currently exists which can be used to assess instrument performance in this manner.
Thus there is still an existing need for such a single polypeptide standard.